1. Technical Field
The present invention relates to a semiconductor device and a method of manufacturing the semiconductor device, and particularly to a semiconductor device including an electrical fuse and a method of manufacturing the semiconductor device.
2. Related Art
Hitherto, in semiconductor devices having a multilayer wiring structure in which a wiring and an insulating interlayer are used, the interconnect is buried in the inside of a groove provided in the insulating interlayer. The interconnect having such a wiring structure can be used as a fuse.
As one method of cutting the fuse, there is a method of irradiating a cutting portion of the fuse with a laser. Japanese Unexamined Patent Publication No. H11-97542 discloses a configuration in which the fuse is cut by laser irradiation. Here, as shown in FIGS. 10A and 10B, a lower metal wiring 2 and an upper metal wiring 4 are electrically connected to each other by a metal plug 5. A metal wiring 6 is provided to both sides of the upper metal wiring 4 in parallel with the upper metal wiring 4. An insulating interlayer 7 is formed on an insulating interlayer 3, the upper metal wiring 4, and the metal wiring 6, and a void 8 is provided in the insulating interlayer 7. A passivation film 9 is formed on the insulating interlayer 7.
In such a fuse structure, there is performed irradiation with laser light which is not absorbed in the passivation film 9, and is absorbed when the laser light reaches the upper metal wiring 4 made of aluminum. Thereby, the temperature of the aluminum rises, the aluminum evaporates explosively, the insulating interlayer 7 of the lateral face of the upper metal wiring 4 is blown off, and the lower metal wiring 2 and the upper metal wiring 4 are electrically isolated from each other due to the nonexistence of aluminum on the metal plug 5 (FIGS. 11A and 11B). Thereby, since the passivation film 9 exists in any of states before and after cutting of the fuse, moisture is not infiltrated into the insulating interlayer 7 formed of a fluoridated silicon oxide film having high hygroscopicity, and thus a problem in reliability does not occur. Here, the void 8 is provided in order to prevent aluminum evaporated during cutting from being deposited again. That is, the void 8 serves as a shelter of aluminum evaporated during cutting, and thus it is possible to prevent aluminum from being deposited again.
However, in the method of cutting the fuse with a laser, it is difficult to narrow down the cutting location. For this reason, an electrical fuse for melting down the fuse using a current is developed. For example, Japanese Unexamined Patent Publication No. 2002-197884 discloses a configuration in which for the purpose of easily melting down the electrical fuse using a current, a portion of a metal layer forming the electrical fuse is narrowed, or is formed in a shape which is once bent at a right angle, to thereby cause a current to be focused on a bent portion.
Meanwhile, Japanese Unexamined Patent Publication No. 2004-193431 discloses a configuration in which the air gaps are provided in order to lower a capacity between the wirings.